This document is the IBM Mobile Systems ThinkPad Computer Hardware Maintenance Manual, which describes the features and characteristics of the ThinkPad T20, T21, T22, T23, and ThinkPad Dock.
This Service Manual is intended for trained service personnel who need to maintain, diagnose, and repair IBM ThinkPad T20, T21, T22, and T23 laptops. It includes safety notices, specifications, FRU replacement procedures, and diagnostic test guidance.
The manual is organized into common safety and handling sections, product‑specific overviews, a full parts list, and detailed troubleshooting indexes such as Symptom‑to‑FRU, error codes, and beep patterns. Power‑cord information for docking stations and regional variations are also provided.